Octopus Evades Predators by Mimicking Toxic Sea Creatures

The Indonesian mimic octopus has the boldest defense strategy of any of its cephalopod cousins, and now scientists know how that strategy evolved. Rather than blending into the scenery, the octopus mimics the swimming behavior and shape of a variety of toxic sea creatures — like flatfish and sea snakes — and displays bold color patterns that shock predators.

Scientists have reconstructed the family tree and unique evolution of the Indonesian mimic octopus, Thaumoctopus mimicus, using DNA sequences from 35 of its relatives. The study will be published in September in Biological Journal of the Linnaean Society.

For the study, scientists focused on mimic’s ability to swim on the sea floor like a flatfish, of which there are several toxic varieties in the region where the octopus lives (video above). The analysis revealed that the behavior evolved in three key steps.

First, mimic octopus ancestors started switching on bold colors to shock predators when camouflage failed. Next, they learned to swim like sea-floor–dwelling fish and developed longer arms that facilitate the motion. Third, they combined the bold color patterns and flatfish swimming technique, and started doing it while out on daily forays and resting.

“While T. mimicus‘ imitation of a flatfish is far from perfect, it may be good enough to fool predators where it lives, in the world’s center of marine diversity,” biologist Healy Hamilton of the California Academy of Sciences, co-author of the study, said in a press release. “In the time it takes a predator to do a double-take, the octopus might be able to get away.”

The Indonesian mimic octopus was first discovered by scientists in 1998.